[Content Gap] Add AI and generative AI governance resource

## What needs to change
The site currently has almost no coverage of AI governance despite it being one of the most active areas of federal data policy. Only two resources carry the AI keyword and neither addresses generative AI, large language model use, or AI risk management. This is the highest priority content gap on the site.

## What to create
A new resource page or a curated set of listings covering federal AI governance. The goal is not to write original guidance but to surface and link to the authoritative resources that already exist.

## Suggested resources to include
Research and verify each of the following is current and linkable before adding:

**Executive orders and policy:**
- Executive Order 14110 on Safe, Secure, and Trustworthy AI (October 2023) — check current status as EOs can be revoked or modified
- OMB M-24-10 (Advancing Governance, Innovation, and Risk Management for Agency Use of AI, March 2024) — verify this is still in effect
- OMB M-24-18 (Memorandum on AI in the Federal Government) — verify current status

**Standards and frameworks:**
- NIST AI Risk Management Framework (AI RMF 1.0) at https://airc.nist.gov/
- NIST Generative AI Profile (NIST AI 600-1) at https://airc.nist.gov/Docs/1

**Federal CDO Council:**
- Check https://resources.data.gov for any recent CDO Council AI-related publications not yet listed on the site
- Check https://www.cdo.gov for recent AI guidance from the CDO Council

## How to add it
Each resource should be added as a separate summary file in `pages/_summaries/` following the same front matter format as existing guidance entries. At minimum each entry needs:
- `title`
- `url`
- `description`
- `source`
- `keywords` — include `AI` and `data-governance`
- `category` — Guidance

If there are enough resources to justify it, consider also creating a new keyword page for `generative-ai` following the pattern of existing keyword pages in the repo.

## How to verify
Visit https://resources.data.gov/keywords/ai/ and confirm the new resources appear. Confirm they also appear under https://resources.data.gov/categories/guidance.